Putida isomerase

During the period of time when the nature of the 19-nortestosterone acetate-dependent photoinactivation was under investigation, a new bacterial steroid isomerase was obtained from extracts of Pseudomonas putida (Biotype B) in nearly homogeneous form and some of its physical and enzymatic properties were characterized (64, 65, 66). The putida isomerase is similar in its molecular weight and quaternary structure to the testosteroni isomerase. Chemically, the most striking difference between the two isomerases is the presence of four residues of cysteine per polypeptide chain of the putida isomerase whereas no cysteine or cystine is present in the testosteroni isomerase. N-Terminal sequence analysis of the putida isomerase demonstrated substantial sequence homology between the two enzymes. 

Junker F, JL Ramos (1999) Involvement of the cis/trans isomerase Cti in solvent resistance of Pseudomonas putida DOT-TIE. J Bacterial 181 5693-5700. 

A 3-Ketosteroid isomerase (3-KSI). This enz)mie catalyses the allylic isomerization of the 5,6 double bond of A5-3-ketosteroids to the 4,5 position by stereospecific intramolecular transfer of a proton. The enz)mie has been isolated from bacteria, and especially the 3-KSIs from Comamoms testosteroni and Pseudomonas putida have been investigated (Smith et al, 1980). The gene coding for the 3-KSI of Pseudomonas putida biot) e B has been cloned and its nucleotide sequence determined (Kim et al, 1994). 

Smith, S.B., Richards, J.W. and Benisek, W.R (1980) The purification and characterization of A5-3-ketosteroid isomerase from Pseudomonas putida, a cysteine-containing isomerase. /. Biol. Chem., 255, 2678-84. 

K. Miyamotoa, K. Okuroa, H. Ohta, Substrate specificity and reaction mechanism of recombinant styrene oxide isomerase from Pseudomonas putida. Tetrahedron Lett. 48 (2007) 3255. 

The optimal pH of isomerases is 7-8. The cis-trans isomerase in the solvent-tolerant bacterium Pseudomonas putida S12 mainly works for the transformation of palmitoleic acid (9-ds-C16 l) to its geometrical isomer 9-trans-C16 l. For example, in case of the addition of 3-nitrotoluene, it gives a final cis/trans ratio of 32 68 [25], The cis-trans isomerase isolated from Pseudomonas sp. strain E-3 is flexible enough to convert the double bonds at positions 9,10, or 11, but not those at positions 6 or 7, of ds-monounsaturated fatty acids having a chain length of 14, 15, 16, or 17 carbon atoms. CTI is 400- to 450-fold more efficient than the reverse reaction [22], and occurs on fatty acids in the free form. However, in the presence of... 

Since the involvement of the heme-binding motif was provided by site-directed mutagenesis experiments on the cti gene of Pseudomonas putida P8, which causes the loss of isomerization activity [29], the observed strong isotope fractionation provided evidence that isomerization includes a binding of the substrate to the active center of heme-containing protein of the cytochrome c-type. Future research on the structure of cis-trans isomerase should allow the mechanism to be properly defined. 

The reaction catalyzed by aconitate isomerase Pseudomonas putida) in solvent involves 4% tritium transfer between the pro- S) positions of cis- and trani-aconitate 119) [Eq. (26)] ... 

The X-ray crystal structure of P. putida muconate lactonizing enzyme (cycloisomerase) was determined in 1987, and was found to contain an a/(i barrel fold, also found in triosephosphate isomerase and enolase. Remarkably, the structure of P. putida mandelate racemase, which catalyzes a mechanistically distinct reaction earlier in the same pathway, was found in 1990 to have a homologous structure, indicating that the structural fold of the enolase superfamily is able to support a range of enzyme-catalyzed reactions. The P. putida 3-carboxy- r, x-muconate lactonizing enzyme, in contrast, shares sequence similarity with a class II fumarase enzyme, and determination of its structure in 2004 has shown that it shares the same fold as the class II fumarase superfamily, hence these two catalysts of similar reactions have evolved from different ancestors. ... 

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